Method of forming semiconductor chips, the semiconductor chips so formed and chip-stack package having the same

ABSTRACT

Provided are methods of fabricating semiconductor chips, semiconductor chips formed by the methods, and chip-stack packages having the semiconductor chips. One embodiment specifies a method that includes patterning a scribe line region of a semiconductor substrate to form a semiconductor strut spaced apart from edges of a chip region of the semiconductor substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This U.S. non-provisional patent application claims priority under 35U.S.C. § 119 to Korean Patent Application No. 2006-63936 filed on Jul.7, 2006, the entirety of which is hereby incorporated by reference.

BACKGROUND

1. Field of the Invention

The present invention relates to method of forming semiconductor chips,to the semiconductor chips so formed, and to a chip-stack package havingthe semiconductor chips.

2. Description of the Related Art

As electrical appliances are continually reduced in both size andweight, various methods of packaging semiconductor chips have beenstudied to replace the conventional method of wire-bonding in an attemptto help reduce the size and weight of the semiconductor packages used inthe electrical appliances. Some of these packaging methods involveflip-chip bonding, wafer-level packaging, wafer-level stack packaging,and chip-stack packaging.

In the case of the chip-stack packaging, stacked semiconductor chips areelectrically connected by through vias formed in the semiconductorchips. This may result in shorter length interconnects, which mayprovide high performance, high speed, low power consumption, andmicrominiaturization as compared to some of the other conventionalpackaging methods.

However, a semiconductor chip built in a chip-stack package typicallyinvolves a complicated fabrication process. This fabrication processtypically includes the following steps. A connection hole is formed atedges of the semiconductor chip and filled with a metal layer, and thenthe metal layer is polished. However, before the connection hole isfilled with the metal layer, an insulation layer, a barrier metal layer,and a seed layer are generally sequentially and conformally formed inthe connection hole. The insulation layer helps prevent a leakagecurrent. The barrier metal layer helps prevent the metal layer frombeing diffused. The seed layer aides in conformally and easily formingthe metal layer. These processes for forming the semiconductor chipbuilt in the chip-stack package, however, are very complicated.Furthermore, the thickness of the insulation layer formed in theconnection hole is restricted by a width of the connection hole.Therefore, it is not easy to form the insulation layer having sufficientthickness to prevent the leakage current.

SUMMARY

The present invention provides a method of forming a semiconductor chipthat can be simplified, while helping reduce a leakage current. Thepresent invention also provides a semiconductor chip formed by themethod and a chip-stack package having the semiconductor chip.

An example embodiment of the present invention provides a method offabricating the semiconductor chips. The method includes patterning ascribe line region of a semiconductor substrate to form a semiconductorstrut spaced apart from a chip region of the semiconductor substrate. Aconductive pattern may be formed at a surface of the semiconductorstrut. Alternatively, impurity ions may be doped into the semiconductorstrut. This shows that the semiconductor strut may be used as a means ofan outer connection terminal. Therefore, the method of fabricatingsemiconductor chips according to the present invention does not need aseed layer, a barrier metal layer, and an insulation layer resulting ina significantly simplified fabrication process. Furthermore, when thesemiconductor strut is formed, it is easy to control the gap between thesemiconductor strut and the semiconductor substrate to prevent a leakagecurrent. Additionally, sizes and features of the semiconductor strut maybe easily controlled to be suitable for sizes and features of asequential bump, thereby improving a reliability of semiconductor chips.

More particularly, the method of fabricating a semiconductor chipaccording to this example embodiment includes preparing a semiconductorsubstrate including a chip region and a scribe line region, forming abonding pad on the chip region of the semiconductor substrate, forming aprotective layer exposing a portion of the scribe line region and thebonding pad but covering the semiconductor substrate, forming aredistribution pattern contacting the bonding pad and covering theexposed scribe line region of the semiconductor substrate, and removinga portion of the semiconductor substrate located below theredistribution pattern at the scribe line region to form a semiconductorstrut contacting the redistribution pattern.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIGS. 1 through 4 are plan views illustrating a method of forming asemiconductor chip according to an embodiment of the present invention;

FIGS. 5 through 11 are sectional views illustrating a method of forminga semiconductor chip according to an embodiment of the presentinvention;

FIG. 12 is a sectional view of a chip-stack package according to anembodiment of the present invention;

FIG. 13 is a plan view illustrating a method of forming a semiconductorchip according to another embodiment of the present invention;

FIGS. 14 and 15 are sectional views illustrating a method of forming asemiconductor chip according to another embodiment of the presentinvention; and

FIG. 16 is a sectional view of a chip-stack package according to anotherembodiment of the present invention.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

In the drawings, the thickness of layers and regions are exaggerated forclarity. It will be understood that when an element such as a layer,region or substrate is referred to as being “on” another element, it canbe directly on the other element or intervening elements may also bepresent.

Furthermore, relative terms, such as “beneath”, may be used herein todescribe one element's relationship to another element as illustrated inthe Figures. It will be understood that relative terms are intended toencompass different orientations of the device in addition to theorientation depicted in the Figures. For example, if the device in theFigures is turned over, elements described as “below” other elementswould then be oriented “above” the other elements. The exemplary term“below”, can therefore, encompasses both an orientation of above andbelow.

It will be understood that although the terms first and second are usedherein to describe various regions, layers, and/or sections, theseregions, layers, and/or sections should not be limited by these terms.These terms are only used to distinguish one region, layer, or sectionfrom another region, layer, or section. Thus, a first region, layer, orsection discussed below could be termed a second region, layer, orsection, or vice versa without departing from the teachings of thepresent invention. Like numbers refer to like elements throughout.

FIGS. 1 through 4 are plan views illustrating a method of forming asemiconductor chip according to an embodiment of the present invention.FIGS. 5 through 11 are sectional views illustrating a method of forminga semiconductor chip according to an embodiment of the presentinvention. FIGS. 5, 6, 7, and 11 are sectional views taken along linesI-I′ in FIGS. 1 through 4, respectively. FIGS. 8 through 10 aresectional views illustrating detailed procedures of forming asemiconductor chip of FIG. 11.

Referring to FIGS. 1 and 5, a semiconductor substrate 1 having a chipregion a and a scribe line region b is prepared. Although twoneighboring chip regions a are arranged in FIG. 1, the chip regions amay be arranged repeatedly in horizontal and/or vertical direction(s).The chip regions a are surrounded by the scribe line region b. Althoughnot shown, various devices such as transistors, interconnects,resisters, contacts, etc. may be formed over the semiconductor substrate1. A bonding pad 5 is formed on the semiconductor substrate 1. Thebonding pad 5 may be electrically connected to the various devicesdescribed above. The bonding pad 5 may be formed by forming andpatterning an aluminum layer. A protective layer 3 is stacked on thebonding pad 5. The protective layer 3 may be formed of a double layer ofa silicon nitride layer and a polyimide layer. The protective layer 3functions by protecting the various devices from outer moisture. Theprotective layer 3 is patterned to expose a portion of the bonding pad 5in the chip region a, and a portion of the semiconductor substrate 1 inthe scribe line region b.

Referring to FIGS. 2 and 6, a redistribution pattern 7 is formed on thesemiconductor substrate 1. The redistribution pattern 7 may be formed ofcopper, nickel, or gold by using an electroplating method. Theredistribution pattern 7 may be formed to contact the bonding pad 5 andthe semiconductor substrate 1 exposed at the scribe line region b. Theredistribution pattern 7 may be formed to cross over the scribe lineregion b and to respectively connect at least one of the bonding pads 5of two neighboring chip regions a.

Referring to FIGS. 3 and 7, a portion of the semiconductor substrate 1is etched in the scribe line region b to form a semiconductor strut 9.In detail, the semiconductor strut 9 may be formed using aphotolithography process, a dry/wet etch process, and/or a laserdrilling process. Before forming the semiconductor strut 9, the backsideof the semiconductor substrate 1 may be ground or polished to decreasethe thickness of the semiconductor substrate 1. The semiconductor strut9 is formed to be spaced apart from the chip region a of thesemiconductor substrate 1. Therefore, an opening 8 is formed between thesemiconductor strut 9 and the semiconductor substrate 1, where theopening 8 may expose a portion of the redistribution pattern 7 and theprotective layer 3. The semiconductor strut 9 may be formed to haveisolated-island shapes. However, sizes and shapes of the semiconductorstrut 9 may be changed along features of a bump. The width of theopening 8 may also be changed optionally. The semiconductor strut 9 mayhave the same semiconductor single-crystalline structure as thesemiconductor substrate 1 and, for example, be formed of silicon singlecrystalline.

The semiconductor strut 9 may function as a support when a semiconductorchip is mounted on a mounting substrate such as a printed circuit board.Additionally, when a high voltage is applied on the semiconductor strut9, the semiconductor strut 9 may be conductive. Therefore, thesemiconductor strut 9 may function as an electrode by itself. However,the semiconductor strut 9 may have a larger electric resistance thanother conductors. Therefore, in order to decrease this electricresistance, the following procedures may be carried out.

Referring to FIG. 8, a metal layer 13 is conformally formed on thebackside of the semiconductor substrate 1 to cover the semiconductorsubstrate 1, the semiconductor strut 9, and the protective layer 3 andredistribution pattern 7 exposed by the hole 8. The metal layer 13 maybe formed of aluminum, titanium, tantalum, or tungsten by using asputtering method.

Referring to FIG. 9, a mask pattern 11 is formed on a bottom surface ofthe metal layer 13 on the back side of the semiconductor substrate 1 tocover the semiconductor strut 9. The mask pattern 11, however, may bespaced apart from edges of the chip region a of the semiconductorsubstrate 1. The mask pattern 11 may be a photoresist pattern.

Referring to FIGS. 4 and 10, the metal layer 13 is etched using the maskpattern 11 as an etch mask, thereby forming a metal pattern 13 acovering a bottom surface and a sidewall of the semiconductor strut 9and contacting the redistribution pattern 7. Then, the mask pattern 11is removed. An edge of the metal pattern 13 a may be formed to contactthe protective layer 3. During this process the protective layer 3 mayfunction as an etch stopper. If this process is finished in the state ofFIG. 10, there may exist a risk that the semiconductor strut 9 may beseparated from the redistribution pattern 7 and the protective layer 3because of the weight of the semiconductor strut 9. In order to preventthis separation from occurring, the following process may be carriedout.

Referring to FIGS. 4 and 11, an insulation layer 15 may be stacked andpolished on the backside of the semiconductor substrate 1 to fill theopening 8. A portion of the insulation layer 15 may remain to cover thebackside of the semiconductor substrate 1 in the chip region a by athickness substantially similar to that of the metal pattern 13 a. Afterforming the insulation layer 15, as shown in FIG. 4, the semiconductorchip is cut along line II-II′ in the scribe line region b between thetwo neighboring chip regions a. Therefore, one semiconductor chip may beformed from each of the neighboring chip regions a. Then, a chip-stackpackage may be formed using the semiconductor chip as shown in FIG. 12.FIG. 12 is a sectional view of a chip-stack package according to anembodiment of the present invention.

Referring to FIG. 12, three semiconductor chips are sequentially stackedon a mounting substrate 21. The semiconductor chips are electricallyconnected to each other through bumps 17. Each of the bumps 17 mayinclude a solder ball. The bumps 17 may be formed by various solder-ballattach methods or an electroplating method. The bumps 17 are attached atthe bottom surface of the metal pattern 13 a. Each bump 17 attached onthe metal pattern 13 a, which is located below one of the semiconductorchips, contacts the redistribution pattern 7 of the semiconductor chiplocated below. However, the semiconductor chip located at a lowestposition, which is directly above the mounting substrate 21, isconnected to the mounting substrate 21 by the bumps 17 attached to thelower surface of this semiconductor chip. The mounting substrate 21,which may be a printed circuit board, may be attached to other devicesthrough a plurality of bumps 17 formed on its lower surface. Thesemiconductor chips may be covered by a sealing material 19, such as aplastic resin, on the mounting substrate 21 to be protected from outermoisture or impact.

FIG. 13 is a plan view illustrating a method of forming a semiconductorchip according to another embodiment of the present invention. FIGS. 14and 15 are sectional views illustrating a method of forming asemiconductor chip according to the above embodiment of the presentinvention. FIG. 15 is a sectional view taken by cutting along line I-I′in FIG. 13. FIG. 14 is a sectional view illustrating a detailedprocedure of forming the semiconductor chip illustrated in FIG. 15.

Referring to FIG. 14, an ion-implantation mask pattern 12 is formed tocover a bottom surface and a sidewall of the chip region a of thesemiconductor substrate 1 and expose only the semiconductor strut 9 inthe scribe line region b, where the semiconductor strut 9 and theopening 8 have been previously formed by patterning the semiconductorsubstrate 1 at the scribe line region b in a method such as the onedescribed above FIGS. 5-7. The ion-implantation mask pattern 12 may be aphotoresist pattern. Then, an ion-implantation process is carried out sothat the semiconductor strut 9 is doped by impurity ions 14. This dopingprocess may change the semiconductor strut 9 into a conductivesemiconductor strut 9 a. Then, the ion-implantation mask 12 is removed.If this process is finished in the state of FIG. 14, there may exist arisk that the conductive semiconductor strut 9 a may be separated fromthe redistribution pattern 7 and the protective layer 3 because of theweight of the conductive semiconductor strut 9 a. In order to preventthis separation, the following process may be carried out.

Referring to FIGS. 13 and 15, an insulation layer 15 is stacked on thebackside of the semiconductor substrate 1 and polished to fill theopening 8. Unlike the above embodiment shown in FIG. 11, the insulationlayer 15 may be completely removed on the backside of the portion of thesemiconductor substrate 1 in the chip region a because a metal pattern13 a need not be formed over the conductive semiconductor strut 9 a.Eliminating this extra thickness of the metal pattern 13 a andinsulation layer 15 in the chip region a may reduce the height, andhence overall size, of the resulting semiconductor chip. The insulationlayer 15 insulates the conductive semiconductor strut 9 a from thesemiconductor substrate 1 and supports the conductive semiconductorstrut 9 a by being attached on a sidewall of the conductivesemiconductor strut 9 a. After forming the insulation layer 15, as shownin FIG. 15, the semiconductor chip is cut along line II-II′ in thescribe line region b between two neighboring chip regions a. Therefore,one semiconductor chip may be formed from each of the separated chipregions a. Then, a chip-stack package may be formed using thesemiconductor chip as shown in FIG. 16. FIG. 16 is a sectional view of achip-stack package according to another embodiment of the presentinvention.

Referring to FIG. 16, three semiconductor chips are sequentially stackedon a mounting substrate 21. The semiconductor chips are electricallyconnected to each other through bumps 17. Each bump 17 is attached to abottom surface of the conductive semiconductor strut 9 a. The bump 17attached on the conductive semiconductor strut 9 a located below one ofthe semiconductor chips contacts the redistribution pattern 7 of a lowersemiconductor chip. However, the semiconductor chip located at a lowestposition, which is directly above the mounting substrate 21, isconnected to the mounting substrate 21 by the bumps 17 attached to thelower surface of this semiconductor chip. The mounting substrate 21,which may be a printed circuit board, may be attached to other devicesby a plurality of bumps 17 formed on its lower surface. Thesemiconductor chips may be covered by a sealing material 19, such as aplastic resin, on the mounting substrate 21 to be protected from outermoisture or impact.

Although not illustrated, various embodiments of the present inventionexist. For example, in other embodiments, a metal pattern 13 a may thesurface of the conductive semiconductor strut 9 a. In still anotherembodiment, a semiconductor chip having only the semiconductor strut 9of FIG. 7 may be used. Alternatively, in still another embodiment, aninsulation layer 15 may not be formed, and then, a semiconductor chipwithout the insulation layer 15 may be used.

Accordingly, the present invention provides methods of fabricatingsemiconductor chips, semiconductor chips formed by the methods, andchip-stack packages having the semiconductor chips. The method includespatterning a scribe line region of a semiconductor substrate to form asemiconductor strut spaced apart from the semiconductor substrate of achip region. Therefore, the semiconductor strut may be used as a meansof an outer connection terminal, thereby simplifying a chip stackingarrangement and process. Furthermore, when the semiconductor strut isformed, it may be easy to control the gap between the semiconductorstrut and the semiconductor substrate so that leakage current may beprevented. Additionally, sizes and features of the semiconductor strutmay be easily controlled to be suitable for sizes and features of asequential bump, thereby improving the reliability of the semiconductorchips.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present invention. Thus,it is intended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A method of fabricating a semiconductor chip, the method comprising:preparing a semiconductor substrate comprising a chip region and ascribe line region; forming a bonding pad on the chip region of thesemiconductor substrate; forming a protective layer to cover a portionof the semiconductor substrate, the protective layer exposing a portionof the bonding pad and a portion of the scribe line region; forming aredistribution pattern overlying the protective layer, theredistribution pattern electrically coupled to the exposed portion ofthe bonding pad and covering the exposed scribe line region; andremoving a portion of the semiconductor substrate located below theredistribution pattern in the scribe line region to form a semiconductorstrut contacting the redistribution pattern.
 2. The method offabricating a semiconductor chip according to claim 1, furthercomprising forming a conductive pattern on a sidewall portion of thesemiconductor strut, a bottom portion of the semiconductor strut, and aportion of the redistribution pattern exposed by the removed portion ofthe semiconductor substrate.
 3. The method of fabricating asemiconductor chip according to claim 2, further comprising forming aninsulation layer to fill a gap between the semiconductor substrate andthe semiconductor strut.
 4. The method of fabricating a semiconductorchip according to claim 2, wherein forming the conductive patternfurther comprises forming the conductive pattern on a portion of theprotective layer.
 5. The method of fabricating a semiconductor chipaccording to claim 1, further comprising performing an ion-implantationprocess to implant impurities into the semiconductor strut.
 6. Themethod of fabricating a semiconductor chip according to claim 5, furthercomprising forming an insulation layer to fill a gap between thesemiconductor substrate and the semiconductor strut.
 7. A semiconductorchip comprising: a bonding pad located on a semiconductor substrate; aprotective layer overlying a portion of the semiconductor substrate andexposing a portion of the bonding pad and a portion of the semiconductorsubstrate; a redistribution pattern overlying the protective layer,electrically coupled to the bonding pad and covering the exposed portionof the semiconductor substrate; and a semiconductor strut spaced apartfrom edges of the semiconductor substrate, the semiconductor strutformed to contact the redistribution pattern.
 8. The semiconductor chipof claim 7, further comprising a conductive pattern formed over asidewall and a bottom of the semiconductor strut, the conductive patternformed to contact the redistribution pattern.
 9. The semiconductor chipof claim 8, further comprising an insulation layer filling a gap betweenthe semiconductor substrate and the semiconductor strut.
 10. Thesemiconductor chip of claim 8, wherein the conductive pattern is formedto contact a portion of the protective layer.
 11. The semiconductor chipof claim 7, wherein the semiconductor strut is doped by impurity ions.12. The semiconductor chip of claim 11, further comprising an insulationlayer filling a gap between the semiconductor substrate and thesemiconductor strut.
 13. The semiconductor chip of claim 7, wherein thesemiconductor strut is laterally spaced apart from the edges of thesemiconductor substrate.
 14. The semiconductor chip of claim 7, whereinan upper surface of the semiconductor strut is substantially coplanarwith an upper surface of the semiconductor substrate.
 15. The method offabricating a semiconductor chip according to claim 1, wherein thesemiconductor strut is formed in the scribe line region.